Method of producing face clutches



March 16, 1948. E. WILDHABER 2,437,902

METHOD OF PRoDUciNG FACE CLUTCHES Original Filed Nov. 17, 1942 4 Sheets- Sheet l Snvcntor ERNEST MULDHABER March 16,1948. E. WILDHABER 2,437,902

METHOD OF PRODUCING FACE CLUTCHES Original Filed Nov. 17, 1942 4 Sheets-Sheet 2 Zhmentor ERNEST W/LDH'ABE/a C(ttorneg March 16, 1948. E. WILDHABER METHOD OF PRODUCING FACE CLUTCHE Ofiginal Filed Nov. 17, 1942 4 Sheets-Sheet 3 3nncntor Emvss r W/LDHfiBEE 5 dncrncu March 15, 1948. WILDHABER 2,437,902

METHOD OF PRODUCING FACE CLUTCHES Original Filed Nov. 1'7, 1942 4 Sheets-Sheet 4 252 266 L W z I K256 j 245 l\J -255 5 Zhwentor I [RNEST W/LDHABEE Patented Mar. 16, 1948 UNTED STATES PATENT OFFICE METHOD OF PRODUCING FACE CLUTCHES Ernest Wildhaber, Brighton, N. Y., assignor to Gleason Works, Rochester, N Y., a corporation of New York September 11, 1945.

17 Claims.

The present invention relates to toothed face clutches and to methods of producing such clutches. In a more particular aspect, the invention relates to the construction and production of clash-type toothed face clutch members whose teeth are chamfered at their tops to facilitate engagement of the clutch members while in motion. The present application is a division of my copending application Serial No. 465,862, filed November 1'7, 1942, now Patent No. 2,384,583, granted September 11, 1945, and is directed specifically to the novel method of this invention.

One object of the invention is to provide a process for cutting and ohamfering opposite sides of the teeth of a clutch member in a single operation.

Another object of the invention is to provide a process for cutting and chamfering opposite sides and opposite top edges of the teeth of a clutch member in a single operation as counterparts of cutting and chamfering surfaces of a suitable tool, particularly of a face mill cutter.

Other objects of the invention will be apparent hereinafter from the specification and from the recital of the appended claims.

The first and main requirement for suitable chamfer in a toothed face clutch is that the mating chamfered portions of engaging clutch members he so shaped as to contact at mean points in the lengths of said chamfered portions. This may be fulfilled when mating chamfered portions of the teeth of the engaging clutch members have the same lengthwise direction at mean points in a plane perpendicular to the clutch axis. Secondly, it is desirable that these conditions of contact be fulfilled not only at a mean point in the length of the chamfered part of a tooth, but at other points in the considered plane as well. Thirdiy, it is desirable that the contact between the chamfered portions of the engaging clutch members extend lengthwise of the teeth for a sufficient distance to carry the loads, but preferably not to the ends of the teeth.

'Ioothed face clutch members constructed according to the present invention are made with longitudinally curved side tooth surfaces and longitudinally curved chamfered portions. The sides of the teeth are parts of surfaces of revolution, and the chamfered portions of at least one member of the clutch pair are made surfaces of revolution coaxial with side surfaces of the teeth of said clutch member. Preferably, opposite sides of spaced teeth of each member of a clutch pair are made parts of a common surface of revolution. One member may have the opposite sides of spaced teeth parts of a common convex surface of revolution, while the other member may have the opposite sides of spaced teeth parts of a common concave surface of revolution, or both members may have the opposite sides of spaced teeth parts of common convex surfaces of revolution. The chamfered portions at opposite sides of spaced teeth are also preferably made parts of a common surface of revolution. One or both members may have chamfered surfaces which are parts of surfaces of revolution which are coaxial with the sides of the teeth, or one member may have chamfered surfaces which are coaxial with its side surfaces and the other member may have chamfered surfaces whose axes are inclined to the sides of its teeth. The chamfered parts of longitudinally convex tooth sides may be made longitudinally convex, or longitudinally concave, and vice versa, the chamfered parts of longitudinally concave tooth sides may be made either longitudinally concave or longitudinally convex. In all cases, the chamfered portions of mating teeth are made to extend in the same lengthwise direction, preferably radial of the clutch axis, at points of contact, and the side surfaces of mating teeth are also made to extend in the same lengthwise direction, preferably radial of the clutch axis, at points of contact.

The tooth sides may be cut simultaneously with the chamfering of the teeth, or side-cutting and chamfering may be effected in separate operations. Preferably the tooth sides and chamfers of at least one member of a clutch pair are cut simultaneously.

In the cutting operation, a face mill cutter is preferably employed that is of sufiiciently large diameter to operate simultaneously in two spaced tooth zones of the work. This is true, whether it is the tooth sides that are to be cut or the chamfers that are to be produced. In any case,

in order to obtain the desired lengthwise direc tion of the tooth sides or of the chamfers, the cutter employed must be positioned so that its axis lies in a plane containing the clutch axis and intersects normals at mean points to the side and chamfered portions of a clutch tooth. The cutter is rotated in engagement with the work while a relative depthwise feed movement is produced between the cutter and the work. When the opposite sides of spaced teeth have been cut to full depth, the cutter is withdrawn, and the blank indexed. Then the cycle begins anew. Thus, side tooth surfaces and chamfer surfaces are cut on the clutch member which are counterparts of the cutting tool or tools and which extend in the desired direction.

The depthwise feed motion is preferably ef- 3 fected in a direction inclined to the axis of the cutter so that cutting will be done by the tip cutting edges and the side-cutting edges at one side only of the cutter, even when cutting from the solid, and the other side of the cutter will be relieved of cutting. This permits of sharpening the cutter blades so as to have side-cutting edges at one side only. This type of cutter is particularly advantageous because it produces a fine finish.

By using a face mill cutter that has side-cutting edges at one side that are shaped for part of their height to produce the desired profile'shapes on the sides of the teeth of the gear, and that have the rest of their heights shaped to produce the desired chamfer, side surface and chamfer surfaces can be produced simultaneously. They will either be both longitudinally convex or both longitudinally concave, depending on whether the cutting and ohamfering edges are both inside or both outside cutting edges. By using a face mill cutter that has side-cutting edges at one side shaped to produce the desired profile shapes on the sides of the teeth of the gear, and chamfering edges at its opposite side that are shaped to produce the desired chamfers, sides of teeth or tooth spaces can be cut and opposite sides of those teeth or tooth spaces chamfered in the same operation. If the side-cutting edges are inside cutting edges and the chamfering edges are outside cutting edges, the tooth sides will be longitudinally convex and the chamfers will be longitudinally concave, while if the side-cutting edges are outside cutting edges and the chamfering edges are inside cutting edges, the tooth sides will be longitudinally concave and the chamfers will be longitudinally convex.

Several difierent embodiments of the invention are illustrated in the accompanying drawings, in which:

Fig. 1 is a sectional view of a pair of engaging toothed face clutch members made according to one embodiment of this invention, the section being taken in a mean plane, hereinafter referred to as the pitch plane, which is perpendicular to the clutch axis;

Fig. 2 i a fragmentary elevational view of the pair of clutch members;

Fig. 3 is a diagrammatic view, showing one of the clutch members, partly in section in the pitch plane and partly in plan, and illustrating the principles underlying the cutting and chamfering of the tooth surfaces of this member;

Fig. 4 is a part elevational, part sectional view, further illustrating one method of simultaneously cutting and chamfering tooth surfaces of this clutch member according to the present invention;

Figs. 5 and 6 are views similar to Figs. 3 and 4, respectively, showing one method of simultaneously cutting and chamfering teeth of the mating clutch member according to this invention;

Figs. 7 and 8 are views similar to Figs. 5 and 6, respectively, showing how the tooth surfaces of one member of a clutch pair may be out and chamfered simultaneously according to a difierent embodiment of this invention;

Figs. 9 and 10 are views similar to Figs. 5 and 6, respectively, illustrating the simultaneous cutting and chamfering of the tooth surfaces of a clutch member according to a further embodiment of the invention;

Fig. 11 is a fragmentary axial sectional view of a preferred form of face mill cutter with inside cutting blades made to practice this invention;

Fig. 12 is a normal section through a tooth of a clutch member made according to the embodiment of the invention illustrated in Figs. 3 and 4;

Fig. 13 is a diagrammatic view illustrating the principle on which the present invention is based and showing further why a convex chamfer may be superior to a chamfered surface which is of straight profile;

Fig. 14 is a similar view, showing diagrammatically a modified form of convex chamfered surface;

Fig. 15 is a part elevational, part sectional view on an enlarged scale of a pair of clutch members made according to one embodiment of this invention and having chamfered portions of convex profile shape;

Fig. 16 is a fragmentary axial sectional view through cutter and clutch member, illustrating more or less diagrammatically the operation of cutting and chamfering simultaneously according to a further modification of the invention the teeth of one member of a clutch pair;

'Fig. 17 is a similar view, showing the cutting of the side tooth surfaces of the mating clutch member;

Fig. 18 is a similar view, showing the chamfering of the tooth surfaces of this latter clutch member;

Fig. 19 is a view, corresponding to Fig. 16, showing the simultaneous cutting and chamfering of the teeth of a clutch member according to a still further embodiment of the invention;

Figs. 20 and 21 are views, corresponding to Figs. 17 and 18, respectively, showing the cutting and chamfering in separate operations, respectively, of the clutch member which is to engage with the clutch member cut by the process of Fig. 19;

Fig. 22 is an enlarged axial sectional view of a pair of mating clutch members out and chamfered according to the modification of the invention illustrated in Figs. 16 to 18 inclusive; and

Fig. 23 is an enlarged axial sectional view of a pair of clutch members out and chamfered according to the modification of the invention 11- lustrated in Figs. 19 to 21 inclusive.

Reference will be made first to the embodiment of the invention illustrated in Figs. 1 to 6 inclusive. Here 30 and 3| denote, respectively, the two members of a clutch pair. The member 30 has teeth 32 which extend generally radially of the clutch axis 33 and whose opposite sides 34 and 35 are longitudinally concave. The mating clutch member 3| has teeth 39 which extend generally radially of the clutch axis 33 and whose opposite sides 40 and 4| are longitudinally convex. The teeth 32 of member 30 are chamfered along their top edges on both sides, as denoted at 36 and 31. In the instance shown, the chamfered portions 36 and 31 of the teeth extend generally radially of the clutch axis 33 and are of concave lengthwise shape like the tooth sides 34 and 35. The teeth 39 of member 3| are chamfered along their top edges on both sides, as denoted at 42 and 43, and in the embodiment shown the chamfered portions 42 and 43 extend generally radially of the clutch axis 33 and are of convex lengthwise curvature like the tooth sides 40 and 4|. In the instance illustrated, the opposite sides of the teeth of both clutch members are of zero pressure angle, that is, their profiles extend in the direction of the clutch axis 33. They may be made, however, of any desired pressure angle.

For cutting the teeth 32 of the clutch member 30, a face mill cutter 55 is used whose blades 59 have outside cutting edges 56 and outside chamfering edges Ed. The side-cutting edges 58 are of positive pressure angle and extend for part only of the effective cutting height of the cutter, while the chamiering edges 55 extend for the rest of the efiective cutting height of the cutter and re of greater positive pressure angle than the sidecutting edges 55. The chambering edges 54 may be formed on the same blades 59 of the cutter as the side-cutting edges 58, or they may be formed on separate blades so that one blade may cut on the sides of the teeth of the work and another blade may chamfer the teeth along their top edges.

The cutter 55 is tilted with reference to the clutch blank so that its axis is intersects the clutch axis 33 and is inclined to the pitch plane d? of the clutch member at an angle substantially equal to the pressure angle of the outside cutting edges 555 of the cutter so as to produce tooth sides of zero pressure angle on the clutch member. The diameter or" the cutter E is preferably so chosen and the cutter is preferably so positioned that it will cut and chamfer opposite sides of spaced teeth of the clutch member in a single operation as, for instance, the opposite sides 3 in and 35b of teeth 32a and 32b and the chamfered portions 35a and tlb of these same teeth.

As already stated, the side surfaces of the teeth of clutch member 35 have a radial direction at mean points in their lengths, such as at point 57 of tooth side 3552). Hence, the normal 58 to a tooth side 35b at mean point 5? is perpendicular to the mean radius 33-57 (Fig. 3) of the clutch member. As also previously explained, the chamfered portions of the teeth of clutch member 38 also have a radial direction at mean points in their lengths, such as at point 66 of chamfered surface 3%. Hence, the normal 52 at said mean point til is perpendicular to the radius 33-853 of the clutch member at said mean point.

Normal intersects the plane of symmetry $3 containing the axes 33 and 36 of work and cutter in a point tit, and normal .58 intersects said plane of symmetry in point 65. To secure chamfered surfaces which extend generally radiall of the clutch axis as well as side tooth surfaces which extend generally radially of the clutch axis, the cutter axis 36 should be positioned to pass through point 65 as well as through point 65, and the chamfering edge 5!; should be perpendicular to the normal 52 at least at mean point 6%. In this way, the chamfer is correctly positioned even though chamfered portions and tooth sides are parts of concentric surfaces of revolution and may be simultaneously cut.

In the cutting operation, the cutter 55 is rotated on its axis d5 in engagement with the clutch blank while the clutch blank is held stationary on its axis 33, and while simultaneously a relative depthwise feed movement is produced between the clutch member and the cutter. When the opposite sides of two spaced teeth as, for instance, the sides 3% and 35b and the chamfered portions 35a and 3% of the spaced teeth 32a and 32b have been cut to full depth and chamfered, the cutter is withdrawn from engagement with the blank, andthe blank is indexed. Then the cycle begins anew and is repeated until all of the tooth sides have been cut and chamfered.

The feed movement may be in the direction of the cutter axis, but preferably is in a direction inclined to both the cutter and clutch axes so that the inside edges of the cutter blades will do no cutting. All of the blades of the cutter can then be sharpened to be outside cutting blades. Otherwise, alternate blades of the cutter have to be inside and outside blades. In any case, the final shape is applied to the work when the cutter is in full depth position. The feed may be imparted either to the work or to the cutter. The arrow 66 in Fig. 4 indicates the feed direction when the feed is imparted to the work.

The cutting of the side tooth surfaces of the clutch member 3| is effected in a manner similar to the cutting of the side tooth surfaces of the clutch member 3%. A face-mill cutter 70 is used which has a plurality of annularly arranged cutting blades N that have inside cutting edges 12 for cutting the sides of the teeth and inside chamfering edges 13 for ohamfering the teeth along their top edges. The side-cutting edges 12 are of straight profile and the chamfering edges l3 are also of straight profile, but of greater pressure angle than the side-cutting edges 12. The cutter 10 is again of large enough diameter to operate simultaneously in'two spaced tooth zones of the work and is again tilted to produce tooth sides of the desired pressure angle on the work, in this case, zero pressure angle.

Normal 15 to a tooth sid Alb of clutch member 3i at mean point 16 in the tooth length is perpendicular to the mean clutch radius 33--76 because the side surfaces of the teeth extend radially of the clutch axis. This normal intersects the symmetrical plane Tl containing cutter axis 5! and clutch axis 33 in point 78. Normal 79 at mean pointml of the chambered surface 63b is perpendicular to the radius 33-80 and intersects the plane 11 of symmetry in a point 8 E. To cut the side tooth surfaces and chamfered portions simultaneously, then, the cutter axis 5! must pass through both the point it and the point 8|, and the cutter must be positioned so that inside cutting edge i2 is perpendicular to normal 75 at point 15, and chamfering edge '53 is perpendicular to normal 79 at the point corresponding to the point 89.

The cutting and chamfering of the teeth of the clutch member 3i is efiected by rotating the cutter 10 on its axis 5! while producing a relative deptliwise feed movement between the cutter and the work again preferably in a direction inclined to the axes of both cutter and work, such as the direction 84. When the opposite sides of two spaced teeth of the clutch member 3| have been cut and chamfered, the cutter is withdrawn from engagement with the work, and the work indexed. Then the cycle begins anew. Again, the tooth shapes produced are counterparts of the cutting surfaces and finished tooth shape is attained at full depth position.

t is to be noted that the distance l6l8 between mean point '15 and the point of intersection of normal 15 with the plane of symmetry ll (Fig. 5) is equal to distance 58 between mean point 5? and the point of intersection of normal 58 with the plane of symmetry 63 (Fig, 3). Hence, the contacting sides of the two clutch members 3% and BI will match each other along their full length. If less than full length engagement is desired, a smaller cutter may be used in the cutting of the clutch member 3!, or two clutch members having tooth sides of convex lengthwise shape like the member 39 may be meshed together.

It should be noted that the inside cutting edges 12 of cutter 70 have a negative pressure angle, that is, they are inclined away from the cutter axis 51. The cutter l6 must, therefore, be relieved radially as well as axially. This means that the blades of the cutter will have to be adjusted radially after sharpening, but this may be accomplished readily by adjustment of the wedges 85 which are commonly provided for radial adjustment of face mill cutter blades. It should be noted further that while the side-cutting edges and the chamfering edges of both cutter 55 and cutter 10 are of straight profile shape, they may be made of any suitable or desired profile shape. In fact, as will be explained further hereinafter it is advantageous to make the chamfering edges of concave profile shape to produce chamfer surfaces of convex profile.

The outside surface 86 of each cutter blade ll of cutter 10 (Fig. 6) may have, as shown, a straight profile parallel to the direction of relief of the inside cutting blades. In such case,

re outside surfaces of all of the cutter blades may then be ground as parts of a single conical surface concentric with the cutter axis 5I. are non-cutting edges and do not require any relief. Likewise, the inside surfaces 53 of the blades 59 (Fig. 4) of cutter 55 do not require any relief, and since the outside edges of this cutter are axially relieved, in the ordinary manner, the inside surfaces may be shaped to extend in the direction of the cutter axis 46 and may, accordingly, be made parts of a cylindrical surface concentric with the cutter axis.

From the method of cutting the clutch members 30 and SI, it will be seen that opposite sides of spaced teeth of each clutch member lie in a common surface of revolution, and the chamfered portions of opposite sides of spaced teeth also lie in a common surface of revolution. Moreover, the chamfered portions at opposite sides of spaced teeth of each clutch member are surfaces of revolution coaxial with the side tooth surfaces themselves. Thus, the opposite sides 3 3a and 351), respectively, of spaced teeth 32a and 32b of clutch member 30 he in a common conical surface, denoted in Fig. 3 by the line 45, whose axis coincides with axis 45 of cutter 5'5 and is inclined to pitch plane 4? of the clutch member, while the chamfered portions 35a and 37b of the same tooth sides are portions of a conical surface Whose axis is also at 45. Likewise, opposite sides 46a and lib of spaced teeth 39a and 39b of clutch member 3i are parts of a common conical surface, denoted by the circular arc 50 (Fig. 5), whose axis coincides with axis SI of cutter I and is inclined to the pitch line 52 of the clutch member, while the chamfered portions 42a and it-b at these sides of the teeth 39a and 39b are parts of a common conical surface whose axis is also at Teeth 32a and 32b of clutch member 36 and teeth 39a and 39b of clutch member SI are shown in plan in Figs. 3 and 5, respectively.

Clutch members so and SI are preferably provided with plane top surfaces perpendicular to the clutch axis 33 as denoted at 90 and 91, respectively, but each clutch member has a slightly tapering root line or tooth space bottom 02 and 93, respectively, because of the tilt of the cutter in the cutting of each member. The chamfered portions of the teeth of the two clutch members are parallel to the root lines 92 and 93, respectively, and increase in width from the insides of the teeth to the outsides thereof.

A modified form of clutch member and a modified method of producing a clutch member accordin to this invention is illustrated in Figs. 7 and 8. Here a clutch member I00 is shown that has teeth IOI extending generally radially of its These axis I02, The opposite sides I04 and I05 01 the teeth IOI are of straight profile shape and zero pressure angle and they are longitudinally convex. The chamfered portions I06 and I0! of opposite tooth sides are of convex profile shape and of longitudinally concave lengthwise shape. Two teeth IOIc and IOId are shown in plan in Fig. 7.

A face mill cutter H0 is used for cutting this clutch member Illa. This cutter has a plurality of cutting blades III arranged circularly about its axis H2. The blades III have inside cutting edges I I3 of straight profile and negative pressure angle, for cutting the side surfaces I04 and I05 of the clutch teeth, and outside cutting edges IId of concave circular arcuate shape, for chamfering the clutch teeth. The cutter is of sufficient diameter to operate simultaneously in two spaced tooth zones of the work.

The determination of the cutter position and the shape of its cutting edges is based on the sam principles as previously described. Normal I I5 at a mean point I I6 in the chamfered portion of a tooth is perpendicular to the radius I02-I I6 and likewise normal II! at a mean point H8 in a tooth side is perpendicular to the clutch radius IfiZ-IIB. Moreover, the cutter axis II2 should pass through the intersection point II9 of normal II"! with the plane of symmetry I20 containing the work and cutter axes, and through the intersection point I2I of the normal II5 with said plane. The inside edges II3 are inclined to the cutter axis H2 at the angle required in order for the inside edges to cut tooth surfaces of zero pressure angle on the work,

In operation, the cutter is rotated on its axis in engagement with the work, while the work is held stationary on its axis and while a relative depthwise feed movement is efiected between the cutter and the work, preferably in a direction inclined to the axes of both the cutter and the work. When a pair of tooth surfaces of the work have been cut and chamfered, the cutter is withdrawn from engagement with the work and the work is indexed. Then the cycle begins anew.

In this embodiment of the invention, the side cutting edges II3 of the cutter operate on one side of a tooth space and the chamfering edges IM operate simultaneously on the opposite side of the tooth space. Thus the side-cutting edges I I3 cut the opposite sides IBM and I05b of spaced teeth IBM and Hill), respectively, of the clutch member while the chamfering edges II4 are chamfering the teeth IOIc and IOId at opposite sides thereof, respectively, to produce the chamfer surfaces Illic and Ififid. Hence, the chamfer surface at one side of a tooth space will be cut as a surface of revolution of convex profile shape coaxial with the conical surface of revolution containing the side surface at the opposite side of that tooth space. In fact, chamfer surfaces at opposite sides of spaced tooth spaces as, for instance, the chamfer surfaces I 070 and IBM, will be parts of convex surfaces of revolution coaxial with the conical surface of revolution containing the opposite sides Ma and I05b, respectively, of these same two tooth spaces, The axis of these surfaces of revolution coincides with cutter axis I I2. I23 denotes the path traced by a point in the side cutting edge II3 of a blade III of the cutter, or also the line of intersection with the pitch plane of the conical surface containing the tooth sides IBM and I051).

In this embodiment of the invention, tooth spaces and teeth of tapering depth are out which have a greater taper in height from their inner to their outer ends than do the teeth and tooth spaces in the previously described embodiment of the invention. The bottoms or root lines of the tooth spaces of clutch member Iiio are denoted at 22%. The increase in depthwise taper is sometimes desirable, however, especially where concave chamferin portions II t are used in order to obtain a long enough bearing area on the mating chamfered portions Hi and it! of the clutch teeth.

A still further embodiment of the invention is illustrated in Figs. 9 and 10. Here a clutch mem ber :25 is shown that has teeth whose opposide side surfaces I2? and I28 are longitud nally convex and whose opposite chamercd poi 10113 i223 and are longitudinally concave.

The clutch member I25 is cut with a face mill cutter i 35 which has a plurality of cutting blades that are arranged circularly about its axis, These cutting blades have inside cutting of positive pressure angle and concave chamfering edges Elie that are also of positive essure angle but of considerably greater pressure angle than the side-cutting edges I38. The concave chamfering edges idi) are so arranged as to operate on the opposite sides of the clutch teeth from those being operated on by the side cutting edges l'3 3. Hence, one side of a clutch tooth out the opposite side of that tooth chamiered in the same operation. The diameter of the cutter is preferably chosen, as in the previous embodiments of the invention, so as tooperate in two spaced tooth zones of the work =sinultaneously. Thus, the opposite sides Itla and itch of spaced teeth 225a and I251: may be cut and the portions and I2b of these same teeth clia red in a single operation. The path of movement of a point in the side cutting edge m3 of a blade of cutter 535 at full depth position is denoted by the are I65 in Fig. 9.

The principles are followed in determining the shape and position of the cutter I35 for cutting clutch member I25 as have been described with reference to the previously mentioned embodiments the invent-ion. Again the normal til at mean point in the portion iZiEh is perpendicular to a line M l-M2 drawn radially f the clutch -xis M l to the mean point I 32. Again the l W a can point i encliculai the length of this tooth side o the line S lt-Hi6 radial of the Again the cutting edge .533 at should be perpendicular to nores the pitch plane it? (Fig. 1.9) surfaces of zero pressure angle are Again, chamfering edge Ml. cutter axis 537 must be so positioned through the points M8 and H59 of innormals MI and respectivee plane of symmetry 553 conteining the cutter axes.

. d t d of forming the side cutting edge cl it d on separate blades. Since positive pressure angle, the ved the conventional the blade is necesafter sharpening can be com- 1y by sing-1e axial adjustment .ged

interesting feature of the embodiment :of

the invention illustrated in Figs. .9 and 10 is the a normal to a tooth side ii Zfib at I32 on the same blade, these r XI-x .ZJ harpening, but change of position of reversal of the tooth taper. The cutter 135 is tilted outwardly away from the work, whereas in the previously described embodiments of the invention the cutter is tilted inwardly into the work. Hence, the root line or tooth bottom I5I of clutch member I 25 is inclined downwardly from the outer to the inner ends of the clutch teeth. This means that the teeth will increase in height from their outer to their inner ends if the clutch is provided with a plane top surface as denoted at I52 in Fig. 1-0. To obtain uniform tooth height, or more nearly uniform tooth height, from end to end of the teeth, the top surface of the clutch member may be made an internal conical surface.

A clutch member made like the clutch member we of Figs. 7 and 8 or like the clutch member I25 of Figs. 9 and 10 can be mated with a clutch member produced like the clutch member 30 of Figs. 3 and 4, provided that the clutch member 39 has a chamfer surface of convex profile shape produced with a concave cutting edge.

A face mill cutter I55 is shown in Fig. 11 of -.a type that may be employed advantageously practicing this invention. It has a concave, somewhat saucer-like front face I56 which provides greater clearance between the cutter and the work than a plane front face. The slots I5 in the cutter head for the blades I 58 are substantially perpendicular to the concave front face I55 of the cutter and are inclined to the cutter axis I59. The tip cutting edges IGI of the blades are' also inclined to the axis I59 of the cutter and lie in a conical surface IE2 coaxial with the cutter. Where the cutting blades have side cutting edges of zero or negative pressure angle as indicated at I66 in Fig. 11, the shape of the cutter blades is very much simplified by use of a cutter head such as shown at I55.

The use and advantage of concave chamfering edges, that is, of convex chamfered portions -.on the teeth of engaging clutch members will be described further with reference to Figs. 12 to 14 inclusive. Fig. 12 is an enlarged sectional view of a tooth 39 of the clutch member 3| taken parallel to the clutch axis and in a plane containing the normal I5 (Fig. 5). I denotes the straight tooth profile or a profile tangent to the tooth side Mb at a mean point 16 in that tooth side, while I66 denotes a profile tangent to the chamfered portion sec of the tooth at the mean point 88 in the chamfered portion. The tooth side 4112 is of zero pressure angle. Hence, the tangent I65 extends in the direction of the clutch axis. The chamfered portion 43b is inclined to the tooth side Mb and to a plane I61 (Fig. 13) perpendicular to the clutch axis.

In the drawings, the'angle between the tangent I66 and the plane I6! is denoted at T. Because the chamfered surface is by construction radial of the clutch axis at mean point 80, a plane containing the tangent IE6 and tangent to the chamfer surface 431) at mean point will inter sect the plane It! in a radial line, and will intersect the clutch axis 33 in a point of said "line, namely, in a point which projects into the point I58, and which has a distance from the drawing plane equal to the mean clutch radius A, namely, the distance 33-45 (Fig. 5). The plane containing tangent I 65 and tangent to the tooth side 4 ID at point It is perpendicular to the plane of the drawing and contains the clutch axis.

The said two tangent planes intersect in a line which passes through the point of the clutch axis that projects into point I58 and through point 1 1 I 69' a: the'drawing plane, and which is inclined at an angle d to the perpendiculars to the drawing plane. We find that:

d is the dedendum angle, namely, the angle between the root line of the tooth and the pitch plane and as a result is the inclination of the cutter to the pitch plane. This dedendum angle insures'the proper position of the tooth chamfer so that point 80 will be a point of contact between mating chamfer' surfaces of the engaging clutch members. Point 80 is, however, the only point in a chamfered surface of straight profile, such as the chamfered portion 43b, which fulfills the mathematical condition of contact. I have found, though, that proper contact may be extended over the chamfer portions by using chamfers of convex profile shape. Chamfer surfaces of convex profile shape have other advantages which will appear hereinafter.

Let P denote a point in the convex curve I19 whose every point fulfills the mathematical condition of contact. This condition is simply that the angle d should be the same at all points. Angle d depends on the distance I'll-I12; I12 is a point on a tangent I13 to the curve I at point P, and HI is the projection of the point P to the tangent I65. Angle d is the same for all points in the curve I'Ifl when distance I'I I-I I2 is equal to distance I68-I69.

Let :1: denote the abscissa at point P, namely, the distance P-I'I I, and let y denote the ordinate of the point P, namely the distance IB8I'II. Let t denote the angle I II-P-II2, and le X=distance 80-I68, as before. Then,

distance 171172=:z: tan t=X tan T tan i=Z- and b cly x -X tan T and dy=(X tan T)?- By integration, we obtain:

11; y= (X tan T). log.

We are interested primarily in the radius of curvature Ra: at mean point 80. The general formula for the radius of curvature is:

1 g Rx: cos i dx Now:

d y (X tan T) da: 2:

Hence:

(X tan T) dx x The absolute amount of Ra: is then:

105 t X tan T If .'c=X, then:

Rx: cos T. sin T In Fig. 13, the

cos T distance -l69= If the angle 89I'Ii--II5 is also a right angle, then:

distance 80174=the distance distance (80-175) distance (80-174) distance (80-169) cos T sin Tcos T cos Tsin T Rat= distance (80-175) Th curvature radius at mean point 89 may therefore be obtained by drawing line I76 perpendicular to tangent I66 through the intersection point I69 of said tangent with tangent I65, and by drawing line II'I parallel to line I 67 through point I I4 on line I78 which is parallel to line I 95. It will be seen, therefore, that by making the chamfer of suitable convex shape I10, contact between the chamfered portions of mating clutch members may be obtained not only at a mean point 89 in the chamfered surface, but also in any other points desired in the chamfer profile.

Fig. 14 illustrates a case where the curvature circle I80 of the convex chamfered portion of a tooth just touches the tangent I65 to the side profile of the tooth. This occurs when the angle T equals 38 10' and constitutes a convenient chamfering radius. The center of the circle I8!) Fig. 15 shows a pair of clutch members I99 and I9I in engagement. These clutch members are like th clutch members 39 and 3| of Figs.

1 to 6 inclusive except that they have convex chamfered portions. The chamfered portions at opposite sides of the teeth of one member are denoted at I92 and I93, respectively, while the chamfered portions at the mating sides of the teeth of the other clutch member are denoted at I 94 and I95, respectively. The clutch members I and I 9| have plane top surfaces designated at I96 and I9I, respectively, and tapered root surfaces I98 and I99, respectively. The chamfered portions of the teeth increase in width from the inner to the outer ends of the teeth on both members. Mating chamfered portions can be made to contact along their whole lengths or along so much of the length of the teeth as may be desired.

A further modification of the method of producing clutch members according to this invention is illustrated in Figs. 16 to 18 inclusive. One member of the clutch pair is denoted at 290 and the other member at 2!. The teeth of the clutch member 200 have sides cut and chamfered with a single cutter and in a single operation. The cutter is denoted at 205. It has an outside cutting edge 264 which is of positive pressure angle and which extends for a part of the effective cutting height. of the cutter, which is adapted to cut the side surfaces 292 and 263 of the clutch teeth, and it has a concave cutting edge 2%, which is effective for the rest of the effective cutting height of the cutter and which is adapted to out the chamfered portions 201 and 2518 of the clutch teeth. The cutter 2H5 differs only from the cutter 55 (Fig. 4) by having concavely curved chamfering edges 2% instead of straight chamfering edges 5!. The cutter 205 is of a diameter suficient to cut in two spaced tooth zones of the work simultaneously and is positioned with reference to the clutch member 2% according to the principles described with reference to the cuttin of the clutch member 39. Opposite sides of spaced teeth of clutch member 290 are cut and chamfered in a single operation by rotating the cutter 205 on its axis while effecting a relative depthwise feed movement between the cutter and the work.

The tooth sides 232 and 283 are longitudinally concave and of straight profile shape while the chamfered portions 29'! and 2938 of th clutch teeth are longitudinally concave and of convex profile shape. Because of the tilt of the cutter in the cutting operation, the bottoms 2th of the clutch teeth will be inclined downwardly from the inner ends of the teeth to the outer ends thereof. If it is desired to obtain teeth of uniform height from end to end the clutch member 2% may be provided with a conical top surface 2H3 parallel to the root surface 209.

While tooth sides and chamfored portions of the clutch men. er are out in the same operation, the tooth sides and charsfered portions of the mating clutch member dill are cut in separate operations. The tooth sides H2 and M8 are cut with a face mill cutter 25% which has inside cutting edges 2 l ii of positive pressure angle but which is so tilted with reference to the clutch blank as to out side surfaces 2E2 and N3 of zero pressure angle. The diameter of the cutter 2&5 is, as before, selected so that the cutter will operate in two spaced tooth zones of the work simulta neously and out opposite sides of spaced teeth of the work simultaneously as parts of a common conical surface whose axis coincides with the cutter axis 21? and intersects the clutch axis 3l8. Because of the tilt of the cutter, root lines 2|9 of negative taper are produced. This taper, however, matches the positive taper of the top surfaces Ziii oi the clutch member 2 38. lutch member Ziil can be formed with an internal conical top surface 222 to match the root lines 2559 of clutch member 268. It should be noted that the inclination of the root lines of the clutch members is ordinarily quite slight.

The chamfered portions 222 and 223 of the teeth of clutch member Edi are cut by a face mill cutter 225 which has outside cutting edges 22% of concave profile shape. This cutter 225 has. its axis 226 inclined to the axis 218 of the clutch member and intersecting that axis. Its diameter is so chosen that it will operate simultaneously in two spaced tooth zones of the work and it is positioned according to the principles already set forth so as to cut charnfer surfaces 222 and 223 on the clutch member 23! which will have the same lengthwise direction as the lengthwise direction of the mating chamfer surfaces 253'! and see. of clutch member 2th": at points of contact between the mating chamfer surfaces. The cutter is rotated in engagement with the work and the cutter axis 225.

1.4 if necessary fed into depth a suficient distance to produce the chamfer to the desired depth. Then the cutter is withdrawn and the work indexed.

The cutter 225 will produce chamfered portions 222 and 223 of convex profile shape but of concave lengthwise shape on the teeth of the clutch member 213i, and the chamfered portions of spaced teeth of the clutch member will be parts of a common surface of revolution coaxial with Usually a chamfer is produced which is slightly tapered in height from end to end, as shown in Fig. 18. With a separate chamfering operation, however, it is also possible to produce a correct chamfer which is of uniform width from end to end. Control of the bearing lengtl'l on the mating chamfered portions of engaging clutch members is attained by varying the number of teeth skipped between the two tooth zones in which the cutter operates. Fig. 22 shows the clutch members 2% and 23 l in engagement.

A further modification of the invention is illustrated in Figs. 19 to 21 inclusive. Here the two clutch members are denoted at 23s and 23!, respectively. Again one of the clutch members has tooth sides and chamfered portions produced simultaneously, while the other clutch member has its tooth sides cut in one operation and the eeth chamfered a separate operation. In cutting the member a face mill cutter 235 is used which has a plurality of. cutting blades 2% that extend in the direction of its axis 23?. These blades have outside finish cutting edges 23S and outside chamfering edges 239. The side-cutting edges 238 are straight and of zero pressure angle and extend for part of the effective cutting height of the cutter. The chamfering edges 239 are of concave shape and extend for the rest of the effective cutting height of the cutter.

The cutter 235 is positioned according to the principles already described and preferably is made of sufiieient diameter to cut into spaced tooth zones of the work simultaneously, thus finish-cutting longitudinally concave side tooth surfaces of straight profile and longitudinally concave chainfered portions of convex profile on opposite sides of spaced teeth of the work in a single cutting operation. The cutter is positioned so that its axis 2"? is parallel to the axis Edi of the clutch and the cutter is rotated in engagement ith the work while the work is held stationary on its axis and while a relative depthwise feed movement is effected between the cutter and work. Then the cutter is withdrawn and the work indexed. Then the cycle is begun anew.

The tooth sides iidli and 25-3 out on opposite of the teeth of the clutch member 2% are of uniform height from end to end and. the chamfered portions 245 and 2% are also of uniform height from end to end. The tooth sides are parts of cylindrical surfaces in contrast with the pre-- viously described embodiments of the invention which have conical tooth sides. The root lines 2% of the clutch member lie in a plane perpendicular to the clutch axis and the top surface 2d? of the clutch member is also preferably formed to lie in a plane perpendicular to the clutch axis.

Because of the Zero pressure angle of the blades 235, hey must be relieved, not only axially but also radially, and they require to be adjusted radially of the cutter axis after sharpening. This adjustment may be effected in the conventional manner by adjustment of wedges 2 5%.

The side tooth surfaces 252 and 253 of the mating clutch member 23! are cut with a face mill cutter 255 which has inside cutting edges 255 of straight profile and zero pressure angle. This cutter is positioned according to the principles previously described. Its axis 251 is placed parallel to the clutch axis 240 in order to out cylindrical side tooth surfaces on clutch member 21H which will engage with the cylindrical tooth surfaces of clutch member 230. The cutter is rotated in engagement with the work while a relative depthwise feed movement is effected between the cutter and work to cut opposite sides of spaced teeth of the work simultaneously. These sides will be longitudinally convex.

The teeth of clutch member 23l are chamfered by a cutter 260 which has outside cutting edges 26] of concave shape. The cutter is positioned so that its axis 264 intersects the axis 240 of the work and the cutter is of such diameter as to operate in two spaced tooth zones of the work simultaneously. The chamfered portions 262 and 263 of the teeth of clutch member 23! are produced, as before, by rotating the cutter in engagement with the work and efiecting such depthwise feed movement as may be required to cut the chamfered portions for their full height. It will be noted that the chamfered portions 262 and 283 increase in width from the inner ends to the outer ends of the teeth. They are of longitudinally concave shape and of convex profile shape and the chamfer surfaces at opposite sides of spaced teeth are parts of a common surface of revolution whose axis coincides with the cutter axis.

The two clutch members 235] and 23! are shown on an enlarged scale in engagement in Fig. 23. It will be noted that the root lines 265 and the top surfaces 266 of clutch member 230 and the root lines 25! and top surfaces 268 of clutch member 23! are plane surfaces perpendicular to the clutch axis 240.

In the case of the clutch members 200 and 238, opposite sides of spaced teeth and the chamfered portions of these sides are counterparts of the cutting surfacesof the cutters 205 and 235, respectively, that is, they are portions of concentric surfaces of revolution. In the case of the mating clutch members 20! and 23!, opposite sides of spaced teeth are portions of concentric surfaces of revolution, and the chamfered portions of opposite sides of spaced teeth are portions of other concentric surfaces of revolution, whose axes are inclined to the axes of the first named surfaces.

The method of the present invention is applicable to grinding as well as to cutting, and grinding may be effected either with a grinding wheel of annular form shaped like the face mill cutter, or with an oscillatory cup-shaped wheel, which is rotated on its axis and simultaneously oscillated to produce the desired lengthwise tooth shape. Where the cup-shaped wheel is used, the angle of oscillation of the wheel is preferably made large enough so that the wheel grinds pposite sides of spaced teeth simultaneously, and thereby achieves the same effect as would be achieved with an annular Wheel operating in two spaced tooth zones of the work. In grinding, wheels of positive pressure angle are preferably used. When the terms cutter and cutting are used hereinafter in the claims it will be understood that they are intended to include grinding wheels and grinding operations.

In general it may be said that while the invention has been described in connection with several embodiments thereof, it is capable of still further modification, and this application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice in the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth and as fall within the scope of the invention or the limits of the appended claims.

Having thus described my invention, what I claim is:

1. The method of cutting and chamfering the teeth of a face clutch member which comprises employing a face mill cutter that has side cutting edges of one pressure angle extending from the tip of the cutter for part of the effective cutting height of the cutter and chamfering edges of greater pressure angle for the rest of the effective cutting height of the cutter, positioning said cutter so that, when it is at full depth cutting position, its axis will pass through points of intersection with a plane containing the clutch axis of normals to a tooth side and a chamfered surface of the work at mean points in the length of said tooth side and chamfered surface, and rotating the cutter in engagement with the work, while holding the work stationary on its axis and while effecting a relative depthwise feed movement between the cutter and the work.

2. The method of cutting and chamfering the teeth of a, face clutch member which comprises employing a face mill cutter that has side cutting edges of one pressure angle extending from the tip of the cutter for part of the effective cutting height of the cutter and chamfering edges of greater pressure angle for the rest of the effective cutting height of the cutter, positioning said cutter so that its axis intersects the work axis and the lengthwise directions of movement of the cutting and the chamfering edges of the cutter at mean points in a tooth zone of the work are radial of the clutch axis, and rotating the cutter in engagement with the work while efiecting a relative depthwise feed movement between the cutter and the work.

3. The method of cutting and chamfering the teeth of a toothed face clutch member which comprises employing a face mill cutter that has side-cutting edges at one side extending for part of the effective cutting height of the cutter and chamfering edges at its opposite side extending for the rest of the eifective cutting height of the cutter and rotating the cutter in engagement with the work while holding the work stationary on its axis and while effecting a relative depth- Wise feed movement betweenthe cutter and the work until the cutter has cut to the full depth of the tooth spaces desired on the work, then withdrawing the cutter from engagement with the Work, indexing the work, and repeating these steps until all of the teeth have been cut and chamfered.

4. The method of producing a pair of engaging tooth face clutch members which comprises simultaneously cutting the side tooth surfaces and chamfering the teeth of one member of the pair by employing a face mill cutter that has outside cutting edges of one pressure angle extending for part of the effective cutting height of the cutter and outside chamfering edges of greater pressure angle extending for the rest of the effective cutting height of the cutter, positioning said cutter so that it will operate simul- 17 taneously in two spaced tooth zones of the work and rotating said cutter in engagement with the work while holding the work stationary on its axis and simultaneously cutting the side tooth,

surfaces and chamfering the teeth of the other member of the pair by employing a face mill cutter that has inside cutting edges of negative pressure angle extending for part of the effective cutting height of the cutter and inside chamfering edges of positive pressure angle extending for the rest of the effective cutting height of the cutter, positioning said cutter so that it will operate simultaneously in two spaced tooth zones of the work, and rotating the latter cutter in engagement with a work piece while holding the work stationary on its axis.

5. The method of producing a toothed face clutch member which comprises employing a face mill cutter that has some cutting edges for cutting the sides of a clutch tooth and other cutting edges for charnfering a tooth along its top edge at the side opposite that operated upon by the first named cutting edges, and rotating the cutter in engagement with a work piece while holding the work stationary on its axis and while eifecting a relative depthwise feed movement between the cutter and work piece until the cutter has cut to the full depth of the tooth spaces of the work, then withdrawing the cutter from engagement with the work, indexing the work, and repeating these steps until all of the teeth of the work have been cut and chamfered.

6. The method of cutting and chamfering the teeth of a toothed face clutch member which comprises employing a cutting tool, that has a side cutting edge extending from the tip of the tool for part of the effective cutting height of the tool and a chamfering edge extending for the rest of the effective cutting height of the tool and moving said tool in a longitudinally curved path across the face of the work so that it cuts in two spaced toothed zones of the work simultaneously, and simultaneously effecting a relative depthwise feed movement between the tool and work while holding the work stationary on its axis until spaced tooth surfaces of the work have been cut to full depth, then withdrawing the tool from engagement with the work, and indexing the work, the tool being so positioned relative to the work that when it is at full depth position, the axis about which it moves will pass through the points of intersection with a plane containing the clutch axis of the normals at mean points to the spaced tooth sides and the spaced chamfered surfaces being cut.

7. The method of cutting and chamfering the teeth of a toothed face clutch member which comprises employing a cutting tool that has a side cutting edge extending from the tip of the tool for a part of the effective cutting height of the tool and a chamfering edge of concave profile shape extending for the rest of the eifective cutting height of the tool, and moving said tool in a longitudinally curved path across the face of the work so that it cuts in two spaced tooth zones of the work simultaneously, and simultaneously effecting a relative depthwise feed movement between the tool and work while holding the work stationary on its axis until spaced tooth surfaces of the work have been cut to full depth, then withdrawing the tool from engagement with the work and indexing the work, the tool being so positioned relative to the work that when it is at full depth position the axis about which it moves will pass through the points of intersection with a plane containing the clutch axis of the 18 normals at mean points to the spaced tooth sides and the spaced chamfered surfaces being cut.

8. The method of cutting and chamfering theteeth of a toothed face clutch member which comprises employing a face mill cutter that has side cutting edges of one pressure angle extending from the tip of the tool for part of the eifective cutting height of the cutter and chamfering edges of greater pressure angle for the rest of the effective cutting height of the cutter, positioning said cutter so that it will cut in two spaced tooth zones of the work simultaneously and so that when it is at full depth position its axis will pass through the points of intersection with a plane containing the clutch axis of normals at mean points to the tooth sides and chamfered surfaces of the work which are being operated on, and rotating said cutter in engagement with the work, while holding the work stationary on its axis and effecting a relative depthwise feed movement between the cutter and work.

9. The method of cutting and chamfering the teeth of a toothed face clutch member which comprises employing a face mill cutter that has side cutting edges extending from the tip of the cutter for part of the effective cutting height of the tool and concave chamfering edges extending for the rest of the effective cutting height of the tool, positioning said cutter so that it will cut in two space toothed zones of the work simultaneously and so that when'it is at full depth position its axis will pass through points of intersection with a plane containing the clutch axis of the normals at mean points to the tooth sides and the chamfered surfaces of the work which are being operated on, and rotating said cutter in engagement with the work while holding the Work stationary on its axis, and effecting a relative depthwise feed movement between the cutter and the work.

10. The method of cutting and chamfering the teeth of a toothed face clutch member which comprises employing a face mill cutter, that has side cutting edges extending from its tip for part of its effective cutting height and concave chamfering edges extending for the rest of its effective cutting height, positioning said cutterso that it will cut in two spaced toothed zones of the work simultaneously and so that when it is in full depth cutting position its axis will pass through the points of intersection with a plane containing the work axis'of the normals at mean points to the tooth sides and the chamfered surfaces of the work which are being operated on, and rotating said cutter in engagement with the work while holding the work stationary on its axis and while effecting a relative depthwise feed movement between the cutter and the work.

11, The method of cutting and chamfering the teeth of a toothed face clutch member which comprises employing a face mill cutter that has side cutting edges extending from its tip for part of its effective cutting height and concave chamfering edges extending for the rest of its effective cutting height, the side cutting and chamfering edges being arranged at the same side of the tool, positioning said tool so that it will cut in two spaced tooth zones of the work simultaneously and so that when it is at full depth position its axis will pass through points of intersection with a plane containing the work axis of the normals at mean points to the tooth sides and chamfered surfaces of the work which are being operated on, and rotating said cutter in engagement with the work while holding the work stationary on its axis and while effecting a relative depthwise feed movement between the cutter and work in a direction inclined to the axes of both the cutter and the work.

12. The method of cutting and chamfering the teeth of a toothed face clutch member which comprises employing a face mill cutter that has side cutting edges at one side extending from its tip for part of its effective cutting height and chamfering edges at its opposite side extending from the rest of its effective cutting height, positioning said cutter so that it will cut in two spaced tooth zones of the work simultaneously and so that when it is at full depth position its axis will pass through the points of intersection with a plane containing the work axis of the normals at mean points to the tooth sides and the chamfered surfaces of the work which are being operated on, and rotating said cutter in engagement with the work while holding the work stationary on its axis and while effecting a relative depthwise feed movement between the cutter and the work.

13. The method of cutting and chamfering the teeth of a toothed face clutch member, which comprises employing a face mill cutter that has side cutting edges at one side extending from its tip for part of the effecting cutting height of the cutter and that has concave chamfering edges at its opposite side extending for the rest of its effective cutting height, and positioning said cutter so that it will cut in two spaced tooth zones of the work simultaneously and so that when it is at full depth position its axis will pass through the points of intersection with a plane containing the work axis of the normals at mean points to the tooth sides and chamfered surfaces of the work which are being operated on, and rotating said cutter in engagement with the work while holding the work stationary on its axis and while effecting a relative depthwise feed movement between the cutter and work.

14. The method of cutting and chamfering the teeth of a toothed face clutch member which comprises employing a face mill cutter that has side cutting edges extending from its tip for part of its effective cutting height and concave chamfering edges extending for the rest of its effective cutting height and arranged to operate on sides of the clutch teeth opposite from the sides onwhich the side cutting edges operate, positioning said cutter so that it will cut in two spaced tooth zones of the work simultaneously and so that when it is at full depth position its axis will pass through points of intersection with a plane containing the clutch axis of the normals at mean points to the tooth sides and the chamfered surfaces of the work being operated on, and rotating said cutter in engagement with the work while holding the work stationary on its axis and while effecting a relative depthwise feed movement between the cutter and the work.

15. The method of cutting and chamfering the teeth of a toothed face clutch member which comprises employing a face mill cutter that has side cutting edges of positive pressure angle extending from its tip for part of its effective cutting height and chamfering edges of greater positive pressure angle extending for the rest of its effective cutting height, and positioning said cutter so that its axis intersects the work axis and so that it will operate in two spaced tooth zones of the work simultaneously and so that when it is at full depth position its axis will pass through the points of intersection with a plane containing the clutch axis of the normals at mean points to the tooth sides and the chamfered surfaces of the work which are being operated on, and rotating said cutter in engagement with the work while holding the work stationary on its axis and effecting relative depthwise feed movement between the cutter and the work.

16. The method of cutting and chamfering the teeth of a face clutch member which comprises employing a face mill cutter that has side cutting edges of one pressure angle extending from the tip of the cutter for part of the effective cutting height of the cutter and chamfering edges of greater pressure angle and concave profile shape extending for the rest of the effec tive cutting height, positioning said cutter so that its axis lies in a plane containing the work axis and intersects normals at mean points to the side and chamfered surfaces to be produced, and rotating the cutter in engagement with the work while holding the work stationary on its axis until the cutter has cut to the full depth of a tooth space of the work, then indexing the work, and repeating these steps until all of the teeth of the work have been cut and chamfered.

17. The method of producing a pair of engaging toothed face clutch members which comprises cutting and chamfering simultaneously tooth surfaces of one member of the pair by positioning a face mill cutter, that has side-cutting edges of one pressure angle extending from the tip of the cutter for part of the effective cutting height of the cutter and chamfering edges of greater pressure angle extending for the rest of the effective cutting height of the cutter, in engagement with a work-piece so that the cutter will operate in two spaced tooth zones of the work simultaneously, and rotating the cutter in engagement with the work while holding the work stationary on its axis, and cutting the side tooth surfaces of the other member of the pair in one operation by positioning a face mill cutter, that has effective side-cutting edges at the opposite side from the side-cutting edges of the first cutter, in engagement with a work-piece so that the second cutter will operate in two spaced tooth zones of the work simultaneously, and rotating the second cutter in engagement with the work while holding the work stationary on its axis, and chamfering the teeth of the second work piece in a separate operation by positioning a face mill cutter that has outside chamfering edges of concave profile shape, in engagement with the work so that the third cutter will cut deeper at the outer ends of the teeth of the second work piece than at the inner end thereof and will operate in two spaced tooth zones of the second work piece simultaneously, and rotating the third cutter in engagement with the second work piece while holding the second work piece stationary on its axis.

ERNEST WILDHABER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

